Gas turbine plant



April 24, 1956 c, GREY 2,743,051

GAS TURBINE PLANT Filed June 28, 1951 W l v /31 27 Inventor x ngz bumu-MAttorney United States Patent GAS TURBINE PLANT John Constantine Grey,Isleworth, England, assignor to Power Jets (Research & Development)Limited, London, England, a British company Application June 28, 1951,Serial No. 234,116 Claims priority, application Great Britain July 3,1950 4 Claims. (Cl. 230-9) This invention relates to the application ofgas turbine plant to the generation for extraneous use, e. g. forblowing a blast furnace, of a supply of combustionsupporting air at apressure substantially sigher than atmospheric and is more especiallyconcerned with the control of such plant.

7 Plant of the kind with which the invention is concerned comprises amain turbine-driven compressor which provides the extraneous air supplyand also feeds a combustion chamber from which the driving turbinereceives hot gas; a separate compressor (the gas compressor) driven bythe same turbine feeds fuel gas to the combustion chamber. The controlof such plant is complicated when it is necessary for the extraneous airsupply to be substantially constant in pressure but variable in amount;mere throttling of the extraneous supply will result in a largerproportion of the delivery of the main compressor being diverted to thecombustion chamber, with consequent variation of turbine speed (and thusdelivery pressure) while an attempt to vary turbinev inlet temperature(and thus to control turbine speed) by throttling the gas supply to thegas compressor will result in an intolerable pressure differentialbetween the deliveries to the combustion chamber from the gas and maincompressors respectively.

The present invention provides gas turbine plant operating on gaseousfuel and designed for the generation for extraneous use of combustionsupporting air at a pressure substantially higher than atmosphericcornprising a main turbine-driven compressor which provides theextraneous air supply and also feeds a combustion chamber from which thedriving turbine receives hot gas, a separate turbine-driven compressorfor supplying fuel gas to the combustion chamber, characterized in thatturbine speed is controlled by diverting fuel gas delivered by the gascompressor before such gas reaches the combustion chamber.

Preferably, the diverting of fuel gas is effected automaticallyresponsive to a variable delivery condition of the main compressor.

This invention may best be understood by reference to the diagrammaticdrawing which shows a bypass valve so positioned as to control theamount of fuel to a combustion chamber in accordance with the outputpressure of the main turbine-driver compressor. Thus, the mainturbine-driver compressor is automatically controlled to accommodatechanging load conditions.

An example of plant in accordance with the invention is illustrated bythe accompanying diagrammatic drawing and comprises a turbine 10 drivinga two-stage,

, 2 l and the remainder being passed to a combustion chamber 16 fromwhich the turbine is fed; the gas compressor 11 delivers to thecombustion chamber by way of a by-pass valve 17. Dual ports 5 in valvemember 18 permit the passage of gas to the combustion chamber 16.

The position of the valve member 18 of the by-pass valve is controlledby an hydraulic relay 19,the supply to which of liquid from a pump 20 iscontrolled by a pilot valve 21. As is well known in the art, said pilotvalve 21 is obviously adapted to control the flow of the spent fluid toa reservoir (not shown) to which pump 20 is connected in a closedsystem. The piston of the relay and that of the valve 21 are linked toone end and an intermediate point respectively of a restoring lever 22,the other end of which is linked to an aneroid capsule 23. The capsuleis mounted in a housing 24, the interior'of which is subject, by way ofa pipe 25, to the pressure obtaining in the delivery duct 14.

With the arrangement illustrated, increase, beyond a predeterminedvalue, of pressure within the duct 14 results in the valve member 18taking up a new position such that a proportion, or a greater proportionas the case may be, of the delivery of the gas compressor 11 isby-passed, being permitted to return, by way of a duct 26, to thereservoir (not shown) from which the gas compressor is fed; thereduction of the fuel supply involves reduction of the turbine inlettemperature and thus of turbine speed, with resultant reduction (i. erestoration) of delivery pressure.

The control system just described may, of course, be applied to plantdiffering in detail (for example, one comprising an axial air compressorfrom which combustion air is bled at an intermediate stage) and offersadvantages by way of fuel economy as 'well as of convenience.

What I claim is:

1. Gas turbine plant comprising an air compressor, a fuel gascompressor, a turbine, shaft means drivingly connecting the turbine tothe said air and fuel gas compressors, a combustion chamber, first ductmeans conveying compressed air from the said air compressor to provide asupply of compressed air for use extraneously of the plant, second ductmeans conveying compressed air from the air compressor to the combustionchamber, third duct means conveying fuel gas from the gas compressor tothe combustion chamber, fourth duct means conveying combustion gasesfrom the combustion chamber to the turbine, at diverting duct positionedin the said third duct means enabling fuel gas tobe diverted from thesaid third duct means instead of passing to the combustion chamber,valve means controlling the How of fuel gas from the third duct meansinto the said diverting duct, actuating means for the valve means, afirst operative connection between the. actuating means and the valvemeans, a control device, a second operative connection between thecontrol device and the actuating means and a connection between thecontrol device and the said first duct means enabling the control deviceto be operated in response to variation of a condition of the compressedair delivered by the air compressor.

2. Gas turbine plant comprising an air compressor, a fuel gascompressor, turbine, shaft means drivingly connecting the turbine to thesaid air and fuel gas compressors, a combustion chamber, first ductmeans conveying compressed air from the said air compressor to provide asupply of compressed air for use extraneously of the plant, second ductmeans conveying compressed air from the air compressor to the combustionchamber, third duct means conveying fuel gas from the gas compressor tothe combustion chamber, fourth duct means conveying combustion gasesfrom the combustion chamher to the turbine, a diverting duct positionedin the said third duct means enabling fuel gas to be diverted from thesaid third duct means instead of passing to h combustion chambevalvemeans controlling the flow of fuel gas from the, third duct meansinto the said diverting duct, actuating means for the valve means, afirst operative connection between the actuating means and the valvemeans, .a pressure-sensitive control device, a second operativeconnection between the control device and the actuating means and aconnection between the control device and the said first duct meansenabling the control device to be operated in response to variation froma given datum of the pressure of the compressed air delivered by the aircompressor.

3. Gas turbine plant comprising an air compressor, a fuel gascompressor, a turbine, shaft means drivingly connecting the turbinetothe said air and fuel gas coma pressors, a combustion chamber, firstduct means conveying compressed air from the said air compressor toprovide a supply of compressed air for use extraneously of the plant,second duct means conveying compressed air from the air compressor tothe combustion chamber, third duct means conveying fuel. gas from thegas compressor to the combustion chamber, fourth duct means conveyingcombustion gases from the combustion chamber to the turbine, atdiverting duct positioned in the said third duct means enabling fuel gasto be diverted from the said third duct means instead of passing to thecombustion chamber, valve means. controlling the flow of fuel gas fromthe third duct means into the said diverting duct, a hydraulic relay, afirst operative connection between the hydraulic relay and the valvemeans, an aneroid capsule, a second operative connection between theaneroid capsule and the hydraulic relay and a connecting pipe betweenthe aneroid capsule and the said first duct means enabling the aneroidcapsule to be operated in response to variation from a given datum ofthe pressure of the compressed air delivered by the air compressor.

4. Blast furnace blowing apparatus incorporating gas turbine plantcomprising an air compressor, a fuel gas compressor, a'turbine shaftmeans drivingly connecting the turbine t the sa d air and fue g scompressors, a combustion chamber, first duct means adapted to conveycompressed air from the said air compressor to a blast furnace, secondduct means conveying compressed air from the air compressor to, thecombustion chamber, third duct means conveying fuel gas from the gascompressor to the combustion chamber, fourth duct means conveyingcombustion gases from the combustion chamher" to the turbine, adiverting duct positioned in :the

said third duct means enabling fuel gas to be diverted from the saidthird duct means instead of passing to the combustion .chamber, valve,means controlling the flow of fuel gas from the third duct means intothe said diverting duct, actuating means for the valve means, a firstoperative connection between the actuating means and the valve means, acontrol device, a second operative connection between the control deviceand the actuating means and a connection between the control device andthe said first duct means enabling the control device to be operated inresponse to variation of a condition of the compressed air delivered bythe air compressor.

References Cited in the file of this patent UNITED STATES PATENTS2,330,558 Curtis Sept. 28, 1943 2,399,046 Larrecq Apr. 23, 19462,416,797 Dodson Mar. 4, 1947 2,422,808 'Stokes June 24, 1947 2,488,969Dietler Nov. 22, 1949 2,557,526 Bobier June 19, 1951 2,559,814 WhittleJuly 10, 1951 2,592,749 Sedille Apr. 15, 1952 a 2,621,476 Sedille Dec.16, 1952 FOREIGN PATENTS 490,978 Great Britain Aug. 24, 1938 941,556France July 19, 1948

